Khandice Schuhmann

lib/queue.js

@@ -1,33 +1,54 @@
+// last in in first out
 class Queue {
-    constructor() {
-        // this.store = ...
-        throw new Error("This method has not been implemented!");
+    constructor(bufferSize = 20) {
+        this.bufferSize = bufferSize;
+        this.store = new Array(bufferSize);
+        this.front = 0;
+        this.rear = 0;
+        this.size = 0;
     }
 
     enqueue(element) {
-        throw new Error("This method has not been implemented!");
-    }
+        // adds element to the end of the queue
+
+        if (this.size === this.bufferSize){
+            return;
+        }
 
+        this.store[this.rear] = element;
+        this.rear = (this.rear + 1) % this.bufferSize;
+        this.size += 1;
+    }
+//removes and returns element form the front of queue and none if queue is empty
     dequeue() {
-        throw new Error("This method has not been implemented!");
+
+        if (this.front === this.rear) {
+            return;
+        }
+        const firstElement = this.store[this.front];
+        this.store[this.front] = null;
+        this.front = (this.front + 1) % this.bufferSize;
+        this.size -= 1;
+
+        return firstElement;
     }
 
     front() {
-        throw new Error("This method has not been implemented!");
+        return this.store[this.front]
     }
 
     size() {
-        throw new Error("This method has not been implemented!");
+        return this.size;
     }
 
     isEmpty() {
-        throw new Error("This method has not been implemented!");
+        return this.size === 0;
     }
 
     toString() {
         let arr;
-        if (this.head > this.tail) {
-            arr = this.store.slice(this.head, this.capacity).concat(this.store.slice(0, this.tail));
+        if (this.front > this.rear) {
+            arr = this.store.slice(this.front, this.capacity).concat(this.store.slice(0, this.rear));
         } else {
             arr = this.store
         }

lib/stack.js

@@ -1,19 +1,25 @@
+//first in last out
+const LinkedList = require("../lib/linked-list.js");
+
+
 class Stack {
     constructor() {
-        // this.store = ...
-        throw new Error("This method has not been implemented!");
+        this.store = new LinkedList();
     }
 
-    push() {
-        throw new Error("This method has not been implemented!");
+    push(element) {
+        return this.store.addLast(element);
     }
 
     pop() {
-        throw new Error("This method has not been implemented!");
+        const removeItem = this.store.getLast();
+        this.store.delete(removeItem);
+        return removeItem;
+
     }
 
     isEmpty() {
-        throw new Error("This method has not been implemented!");
+        return this.store.length() === 0;
     }
 
     toString() {